More recent knowledge of the underlying mechanisms of allergic disorders reveals that the diagnosis and immunotherapy of allergies (atopy) has suffered because of a distinct lack of allergen extracts that are well characterized in terms of total or specific allergen content. Thus, a more adequate means of identifying the relevant allergens and standardizing the specific content of various allergen extracts appears warranted. Studies are designed, using cross-radioimmunoelectrophoresis, to identify the potential clinically relevant allergens contained in representative extracts derived from pollens of trees, grasses, and weeds and shrubs, as well as extracts of foods and animal epidermals. Immunoaffinity chromatography will be used to separate the allergenic components contained within the extracts from the nonallergenic components. The biological activity of the allergens contained within the whole and fractionated extracts will be standardized using RAST inhibition assays. Ultimately, the goal will be to provide extracts that are well standardized, relative to allergen content, based upon their biological potency. The availability of such extracts will assure the certainty of specific diagnosis of allergies as well as insure optimal immunotherapy of the atopic patient.